the original cut of alien3 (aka the special edition) had bishop being a real life person (you see him bleed and he actually screams "i'm not an android" when he gets a good kickin) when the film was re-cut for its cinematic release they purposely changed it so that there's an "is he/isnt he" thing going on... youre not suposed to know... youre left thinking he could possibly be an android... this was probably done so that people would actually have something half decent to discus re: the film, as the rest of it was a bit pants (by aliens standards)

have you seen the special edition by the way? (its on the quadrilogy DVD) the actual PLOT is completely different!!!!! at least half the film is changed! for example in the SE one they do manage to capture the alien in that waste bunker bit! also the chestburster comes out of a cow, not a dog. oh, and there are entire characters that got cut from the theatrical release!